Ultrasonic heterodyning used in speakers in New York: can only be heard by those in the sound beam created (youtube.com)
submitted 9.1 years ago by curiosity38
4743425? 9.1 years ago
I'll save someone else a Google: "Heterodyning is a radio signal processing technique invented in 1901 by Canadian inventor-engineer Reginald Fessenden, in which new frequencies are created by combining or mixing two frequencies."
4743425? ago
I'll save someone else a Google: "Heterodyning is a radio signal processing technique invented in 1901 by Canadian inventor-engineer Reginald Fessenden, in which new frequencies are created by combining or mixing two frequencies."